REAL
i found a solution!
if you mic don't have 'noise cancelation', you need edit you info.plist
in the file /system/library/extensions/voodoohda.kext directory
p. ex., you can change initial parameters, after reboot, fix it!
good lucky

I found a solution.
1.remove the voodoo hda driver (ktext) in installation OR /S*/E*/
2. update the voodoo hda driver (directly from official site)
in my case, the 'internal mic' don't turn off.
good lucky.